Making a perfect grilled cheese sandwich requires one important ingredient: the right amount of time. But how do you know exactly when it's time to flip your sandwich over in the pan to brown the other side? Redditor cousinkyle suggests you watch the butter:

When cooking grilled cheese, put a little butter on the pan next to the sandwich. When the butter browns, that's when it's time to flip.

That helps you with just one side, of course, so stick a little extra butter in the pan once you flip and watch that bit, too. If you prefer a more hands-off approach (and need to make several sandwiches), consider a pair of baking sheets instead.